I think it’s the difference between punching down and punching up. Boomers in general have far more money and power than the people using the term. So complaining that it’s ageist, and comparing it to a homophobic slur will get you about as much traction as white people being offended by cracker, and comparing it to slurs used against African Americans.
Only tangentially related, but when I was a kid I’d write stream-of-consciousness type stuff in a “code” consisting of the first letter of every word. Whenever I run across one of my old notebooks, I spend some time trying to decipher it, generally without much luck. Sometimes it’ll spark a bit of remembrance, like dipping madeleines in tea.